There is an interest in producing certain metals and compounds in the form of very small diameter wires (e.g., 200 nanometers or smaller) because they are expected to have useful electronic properties when in such form. For example, bulk bismuth is a semi-metal with electrons having very high mobility and a small effective mass. Theoretically, bismuth should become a semiconductor with a high thermoelectric power factor if it is prepared in the shape of single crystal wires with diameters such that the energy levels are quantized by the confinement of the electrons. The difficulty, of course, is in making such small diameter wires.
Bismuth wires, about 0.2 micrometers in diameter, have been made by pressing molten bismuth into fine Pyrex capillaries (Michael Gurevitch, "Resistivity Anomaly in Thin Bi Wires: Possibility of a One-Dimensional Quantum Size Effect," Journal of Low Temperature Physics, Vol. 38, Nos. 5/6, 1980). Gurevitch's method uses high pressures, and the pressure necessary scales inversely with wire diameter. Therefore, while the method is successful with 0.2 .mu.m wires, it does not extrapolate easily to wires of smaller diameters. One can calculate that the pressure needed to force molten bismuth into a disk with 0.1 .mu.m pores is about 200 atm, and for the disk with 0.02 .mu.m pores, about 1000 atm are needed. After studying Gurevitch's high-pressure chamber, it was evident that this would be hard to construct and difficult to scale-up for production if a promising device ensued. Therefore, there remains a need for a practical method of producing very small diameter wires, especially wires having a diameter of 0.2 .mu.m (200 nanometers) or smaller.